Workholder

Abstract

A workholder for a machine tool or the like having a power assembly and a work gripping assembly that are separable to permit use of a plurality of work gripping assemblies and associated work gripping jaws of a size and shape to accommodate different workpieces. Work gripping assemblies with jaws pre-qualified to different workpieces can be exchanged quickly and automatically, as by use of a robot, when different parts are to be machined, while a single power assembly remains connected to the machine tool.

We claim: 
     
       1. A power operated workholder assembly comprising a power subassembly and a workholding subassembly separable to permit removal of the workholding subassembly as a unit from the power subassembly without disassembly of either; the power subassembly comprising a first body and power actuable means movable relative to said first body for exerting a force when actuated; the workholding subassembly comprising a second body and work gripping means carried by the second body movable relative to the second body; said power-actuable means and said work gripping means being releasably interengaged to transmit force between the two and disengageable through relative movement of the first and second bodies to allow separation; and means integral with each body to separably retain the first and second bodies tightly together in response to relative movement of the two bodies. 
     
     
       2. The workholder assembly of claim 1 wherein the assembly has a central rotary axis and the work gripping means is movable transversely of the rotary axis. 
     
     
       3. The workholder assembly of claim 2 wherein the power subassembly includes at least one lever pivotably supported by said first body for movement about an axis transverse to said rotary axis and reciprocable means for pivoting said lever. 
     
     
       4. The workholder assembly of claim 3 wherein the lever includes an arm that extends beyond the first body in the direction of said rotary axis. 
     
     
       5. The workholder assembly of claim 1 wherein said work gripping means includes means to guide movement of the work gripping means in a predetermined path relative to the second body and a slide movable in said second body along said guide means. 
     
     
       6. The workholder of claim 5 wherein said slide includes a surface in contact with said power actuable means. 
     
     
       7. The workholder of claim 1, 2, 3, 4, 5 or 6 wherein said means to retain the bodies together includes surfaces that coact through axial relative movement and relative rotary movement of fewer than 360° between the two bodies. 
     
     
       8. The workholder of claim 1, 2, 3, 4, 5 or 6 wherein said means to retain the bodies together includes surfaces that interengage with only relative axial movement of the first and second bodies and that once interengaged positively restrain relative axial movement and relative rotary movement between the two bodies. 
     
     
       9. A method of changing a work gripping device capable of gripping a workpiece with radial force comprising the steps of providing a power subassembly with a first body, power actuable means movable relative to the first body, and means on the first body to connect it to a second body of a workholding subassembly in response to relative movement between said two bodies,   providing at least two separate workholding subassemblies each including a second body, work gripping means carried by the second body for movement relative thereto by said power actuable means when the second body is connected to the first, and means on each of the second bodies to separately connect the second bodies to the first body in response to relative movement between the first and second bodies,   providing the work gripping means of each workholding subassembly with a different contour, and   connecting first one of said work gripping subassemblies as a unit to the power subassembly as a result of relative movement of the first and second bodies and subsequently removing the one and connecting the other and gripping a workpiece of different contour with each of the two work gripping subassemblies.   
     
     
       10. The method of claim 9 including the step of rotating the connected subassemblies and machining a workpiece held by the work gripping means. 
     
     
       11. A workpiece holding system for a rotary machine tool providing work grippers of different contour for use with a common power source, said system comprising: a rotary power assembly including a first body and power actuable means movable relative to the first body for exerting force radially of the axis of rotation of said power assembly,   a first work gripping assembly including a second body and work gripping means supported and guided by said second body for movement radial of said axis, said first work gripping assembly being separate from said power assembly and including means for connecting the second body to the first with the power actuable means coacting with the work gripping means to move the work gripping means radially of said axis,   a second work gripping assembly including a third body and work gripping means supported and guided by said third body for movement radial of said axis, said second work gripping assembly being separate from said power assembly and including means for connecting the third body to the first with the power actuable means coacting with the work gripping means to move the work gripping means radially of the said axis,   the work gripping means of said first work gripping assembly being contoured differently from the work gripping means of said second work gripping assembly, and means on said power assembly for coacting with the means on the first and second work gripping assemblies that connect the second and third bodies to the first to interconnect the power assembly with either of the first and second assemblies in response to relative movement between the first body and the second and third bodies.   
     
     
       12. The system of claim 11 wherein said means to interconnect the power assembly with either of the first and second assemblies includes structures that interengage through relative axial motion. 
     
     
       13. The system of claim 11 or 12 wherein said means to interconnect the power assembly with either of the first and second assemblies includes structures that interengage through relative rotary motion of less than a complete revolution. 
     
     
       14. The workholder assembly of claim 1, 2, 3, 4, 5, 6, 11 or 12 wherein one of said first and second bodies has a tapered pilot member that guides and locates the other of said first and second bodies during relative movement therebetween. 
     
     
       15. The workholder assembly of claim 1, 2, 3, 4, 5 or 6 wherein said means to retain the bodies together includes a spring biased detent in one of said bodies and a member retainable thereby extending from the other of said bodies.